The purpose of the proposed research is to determine both the short- and long-term effects of repeatedly administered delta 9-THC on maternal behavior and infant development in the squirrel monkey. Mothers will be administered the drug orally at different dosages, interdrug intervals, and postnatal periods and the effects of these independent variables will be evaluated with respect to behaviors that pertain to the mother-infant relationship, relationships with other animals, and the infant's development independent of the mother. Various physiological changes, including the excretion of radiolabeled delta 9-THC in the milk of nursing mothers, will also be determined and correlated with behavioral changes.